1. Field of the Invention
The present invention relates to a reversing mechanism of the traveling direction at the end point of travel of a carriage connected to an endless belt stretched between a driving pulley and a follower pulley and reciprocating under the effect of movement of the endless belt, and further, to a reciprocating mechanism of a tool post using the foregoing reversing mechanism in a sheet material cutting device cutting a sheet material with the assistance of a rotary blade traveling while rotating and a fixed blade in contact with the rotary blade.
2. Description of the Related Art
In prior known printers for a terminal such as a cash register, a strip-shaped sheet material wound into a roll is pulled out for printing, and then the necessary portion is cut into a sheet for delivery by a cutter.
Various types of such sheet material cutters are available. The rotary-type cutter is costly to manufacture and creates a relatively high degree of noise and therefore is now being replaced by a cutter based on a combination of a circular rotary cutting blade moving while rotating and a fixed cutting blade formed into a long sheet.
A cutting device of this type will be described below with reference to FIG. 16. A tool post 100 supporting a rotary blade 102 is screw-connected to a screw shaft 101. When the screw shaft 101 is rotated by a driving device such as a motor not shown, the tool post 100 travels on the screw shaft 101 from right to left and vice versa. The rotary blade 102 is supported by bearings for rotation by a shaft 103 provided on the tool post 100, and pressed against a fixed blade 104 by a spring 105, for example. When the screw shaft 101 is rotated by the motor, the tool post 100 travels from right to left and vice versa in FIG. 16, depending upon the rotating direction of the screw. A sheet material transferred vertically in the drawing is cut with the assistance of the rotary blade 102 and the fixed blade 104.
Apart from the above, a well-known device is based on a reciprocating mechanism using an endless wire 110 in place of the screw shaft to serve as the traveling mechanism of the tool post 100, as shown in FIG. 17. This reciprocating mechanism comprises a driving pulley 111, a follower pulley 112, an endless wire 110 stretched between these pulleys 111 and 112, and a motor (not shown) for rotating the driving pulley. The tool post 100 is fixed to the endless wire 110. Rotating the driving pulley 111 moves the endless wire 110, and moves the tool post 100 along a guide 113 provided on a frame as it is pulled by the endless wire 110. In the same manner as in the above-mentioned conventional case, the sheet material transferred vertically in the drawing is cut with the assistance of the rotary blade 102 and the fixed blade 104.
In the devices described above, however, it is necessary, in order to reverse the tool post at the end point of travel, to detect arrival of the tool post at the end point of travel, reverse the rotation of the motor by means of a switching mechanism, reverse the rotation of the screw shaft and the driving pulley, and thus reverse the traveling direction of the tool post. It is therefore necessary to provide the foregoing devices with two sensors to detect the arrival of the tool post at the right and the left end points, and in addition, to provide a switching mechanism for rotating the motor in two directions. This factor prevents reducing the cost of the devices.
In view of the present circumstances as described above, the present inventor carried out extensive studies to develop a reciprocating mechanism of a tool post capable of easily reversing the traveling direction upon arrival of the tool post at the end point of travel while maintaining a uniform direction of motor rotation, and as a result, successfully developed the following:
a reversing mechanism of a carriage capable of reversing the traveling direction of a carriage that is connected to an endless belt stretched between a driving pulley and a follower pulley, and reciprocating under the effect of travel of the endless belt, and upon arrival of the carriage at an end point of travel thereof, without changing the traveling direction of the endless belt; and a reciprocating mechanism of a sheet material cutting device by the application of the foregoing reversing mechanism of a carriage.
The present invention is characterized in that a sliding piece connecting the carriage and the endless belt that travels on the carriage upon arrival of the carriage at the end point of travel, and the traveling direction of the carriage can thus be easily reversed at the end point of travel without changing the rotating direction of the motor or the traveling direction of the endless belt by changing the connecting point of the carriage and the endless belt. Thus, it is possible to reduce the number of sensors provided at the end point of travel and eliminate the switching mechanism for changing the rotating direction of the motor.
When the foregoing reversing mechanism of a carriage is applied for a sheet material cutting device, the sliding piece connecting the tool post and the endless belt is caused to travel on the tool post upon arrival of the tool post at the end point of travel to change the connecting point of the tool post and the endless belt, thereby permitting the traveling direction of the tool post to be easily reversed without changing the rotating direction of the motor or the traveling direction of the endless belt, thus allowing reduction of the number of sensors to be provided at the end point of travel, elimination of the switching mechanism for changing the rotating direction of the motor, and considerable cost reduction of the sheet-cutting device.